DNS reverse lookup errors: zone 1.168.192.in-addr.arpa/IN: has no NS records

I am setting up my first DNS server on Ubuntu 18.04 with bind9 and have worked through the forward lookup and have no errors. When I run:

sudo named-checkzone 1.168.192.in-addr.arpa /etc/bind/reverse.timco.com.db
zone 1.168.192.in-addr.arpa/IN: has no NS records
zone 1.168.192.in-addr.arpa/IN: not loaded due to errors.

Every reference I find has a different format ao I am confused. Here is my reverse-lookup.db:

;
; BIND reverse data file for local loopback interface
;
$TTL 604800
@ IN SOA timco.com. root.timco.com. (
1 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
604800 ) ; Negative Cache TTL
;
;1.168.192.in-addr.arpa. IN NS ns1.timco.com.
;1.168.192.in-addr.arpa. IN PTR ns1.timco.com.

;Name Server Information

3.1.168.192.in-addr.arpa IN NS ns1.timco.com

;Reverse lookup for Name Server

3 IN PTR ns1.timco.com

;PTR Record IP address to HostName


60 IN PTR 70 IN PTR mail.timco.com
5 IN PTR mm.timco.com
7 IN PTR 7030.timco.com
250 IN PTR 7220.timco.com
1 IN PTR 6300.timco.com
2 IN PTR 2930M.timco.com
10 IN PTR cppm.timco.com
30 IN PTR 2012.timco.com
54 IN PTR netedit.timco.com

Can someone shed some light on what is wrong?

Tim